Saving and adding a new line to a csv file with TKinter in Python

Question

SO I've included some of my code having trouble capturing data from the entry fields in TKinter and having them overwrite a csv file. It will overwrite the csv file, but not add a new line at the end of the file like want.

#Variables
File = open(filePath)
Reader = csv.reader(File)
newline='\n'
Data= list(Reader)
main_lst=[]

#Store Button Function
def store():
    with open('./glucose_values.csv', "w+", encoding='utf-8') as f:
        Writer=csv.writer(File)
        csv.writer(["Date","Time","Glucose"])
        csv.writer(newline + main_lst)
        messagebox.showinfo("Information","Saved succesfully")
                
    return None

def Add():
   lst=[timeEnter.get(),dateEnter.get(),bloodEnter.get()]
   main_lst.append(lst)
   messagebox.showinfo("Information","The data has been added successfully")
   return None

#Buttons 
storeButton = Button(root, text="Store", command=store)
storeButton.grid(row=5, column=3 )

addButton = Button(root, text="Add", command=Add)
addButton.grid(row=5, column=1 )

#Enter data area
dateEnter= Entry(root, width = 10).grid(row=13, column=2)
timeEnter= Entry(root,  width = 10).grid(row=14, column=2)
bloodEnter= Entry(root,  width = 10).grid(row=15, column=2)

Kartikeya · Accepted Answer · 2022-03-16T02:15:00.367

1

w+ opens a file for both writing and reading. Overwrites the existing file if the file exists. If the file does not exist, creates a new file for reading and writing.

Therefore, use a instead , as opening a file with the a parameter allows you to append to the end of the file instead of simply overwriting the existing content.

 with open('./glucose_values.csv', "a", encoding='utf-8') as f:
        Writer=csv.writer(File)

EDIT :

csv.writer() function takes a csvfile as argument and you are passing lists:

csv.writer(["Date","Time","Glucose"])

csv.writer(newline + main_lst)

So, the correct way is using writerow() method:

def store():
    with open('./glucose_values.csv', "a+", newline='', encoding='utf-8') as f:
        Writer=csv.writer(f)
        Writer.writerow(["Date","Time","Glucose"])
        Writer.writerow(main_lst)

Also, for appending in the CSV file, it is suggested to use DictWriter() method. Refer here.

edited Mar 16 '22 at 02:15

answered Mar 15 '22 at 02:20

Kartikeya

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Not wiping the whole file anymore, but not getting it to save yet. It won't even make it the message box am I missing something with: csv.writer(["Date","Time","Glucose"]) csv.writer(newline + main_lst) – alex b Mar 15 '22 at 22:39
Traceback (most recent call last): File "C:..\AppData\Local\Programs\Python\Python310\lib\tkinter\__init__.py", line 1921, in __call__ return self.func(*args) File ".\cvs glucose3.0.py", line 27, in store csv.writer(["Date","Time","Glucose"]) TypeError: argument 1 must have a "write" method – alex b Mar 15 '22 at 23:17
`csv.writer()` function takes a csvfile as argument and you are passing lists. Let me edit the answer. – Kartikeya Mar 16 '22 at 02:15
Bene a minute since had time to work on this, but got it to work now and add the items in the way needed. However, when it is done and saved it can't reopen the same CSV again. – alex b Apr 02 '22 at 22:00

Saving and adding a new line to a csv file with TKinter in Python

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